Method and system for partial reporting of missing information frames in a telecommunication system

ABSTRACT

A method and system for partial reporting of missing sequence numbered information frames within a telecommunication system using selective reject (SREJ) frames. Upon receiving a sequence numbered information frame from a transmit terminal, a receive terminal determines if it is out of sequence. If the sequence numbered information frame is out of sequence, the receive terminal further checks the sequence numbered information frame to see if a poll bit has been set. If the poll bit is not set, the receive terminal further checks to see if the sequence numbered information frame is new or retransmitted. If the sequence numbered information frame is new, a list of missing sequence numbers is constructed beginning with the missing sequence number one greater than the largest number in the receive queue and ending with N(S)−1. If the sequence numbered information frame is retransmitted, a list of missing sequence numbers is constructed beginning with the next smaller missing sequence number in the receive queue plus one and ending with N(S)−1. Thereafter, a select reject frame (SREJ) is sent to the transmit terminal containing a list of the out-of-sequence numbered information frame(s) for re-transmittal.

RELATED APPLICATIONS

The present application is related to a co-pending application entitled“METHOD AND SYSTEM FOR SEQUENTIAL ORDERING OF MISSING SEQUENCE NUMBERSIN SREJ FRAMES IN A TELECOMMUNICATION SYSTEM”, Ser. No. 09/227,674,filed on even date herewith and assigned to the assignee of the presentapplication.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates in general to linking in atelecommunication system and in particular to a method for partialreporting of missing information frames by use of selective reject SREJresponse frames. Still more particularly, the present invention relatesto a method and system for continuous link establishment whenout-of-sequence information frames are transmitted between receive andtransmit terminals within a telecommunication or information handlingsystem.

2. Description of the Related Art

Today, most of the transmission between telephone exchanges is digital,but the transmission and the signaling between a local exchange and acustomer is still analogue. Because different users have differentrequirements (telephony, fax, data) in the existing analogue network, itis necessary to use separate telephone lines with separatecharacteristics for the different users. To solve this problem a newuniversal interface has evolved. This new network evolution is calledthe Integrated Services Digital Network (ISDN). ISDN is a versatilenetwork in which all kinds of information technology are transmitted ina digital format between terminals. The ISDN digital access provides theend users with the possibility of initializing end-to-end digitalconnections that can support a variety of services, such as: highquality speech, audio, video. telephony, video conference, as well asfax, data and image transfer capabilities.

To ensure that voice and signaling or data and signaling information canbe transmitted simultaneously in ISDN with no mutual reference, multiplechannels are provided on an ISDN access and are defined by theInternational Telecommunication Union (ITU) in a series of protocolspecifications. These channels are identified as B-channels andD-channels respectively. The B-channels are used for informationtransfer, such as speech, text, data and images. The D-channel is usedfor call control signaling procedures and may also be used to carrypacket-switched data. The call control signaling information on theD-channel is used to establish, supervise and release thecircuit-switched connections being requested for.

Unlike the B-channels, which function as “pipes,” the D-channel isassociated with higher level ITU protocol specifications defined by anOpen System Interconnection (OSI) model. The OSI model has 7 protocolspecification layers in which layers 2 and 3 of the model form thepacket-switched connections associated with the D-channel. Within thelayer 3 protocol specifications for use on the D-channel is acall-control protocol component. This layer 3 signaling protocol istransferred on the D-channel using the layer 2 protocol referred to asthe Link Access Procedure-D-channel (LAPD.) Although the layer 3protocol takes care of most ISDN signaling requirements, the LAPD layer2 protocol utilizes frames that play a very important role in terms oflow-level signaling to ISDN devices. These LAPD frames contain theinformation to ensure that incoming calls are routed to the appropriateISDN device, and pass the addressing information that distinguishes ISDNdevices on a single line from each other.

For continuous information to be transferred between two terminals, asequence numbered information frame is sent along the D-channel from atransmit terminal in a sequencing order to a receive terminal. Thesequence numbered information frame has a predetermined byte structurerecognized at the receive terminal in accordance with the ITU protocolspecification. However, a problem arises due to such effects asmicrowave fadeout and the like, in that one or more sequence numberedinformation frames may be lost during transmission resulting in a lossof the sequencing order. In the past this problem has been overcome byconstructing a selective reject response (SREJ) frame upon receiving anyout-of-sequence numbered information frames. The SREJ frame lists allmissing sequence numbered information frames starting at the firstmissing sequence numbered information frame and ending with the lastmissing sequence numbered frame prior to the received sequenceinformation frame and re-transmitting this complete list. However, thissolution may lead to redundant select reject frames being sent for thesame missing sequence numbered information frames, resulting in a wasteof real-time information processing.

Therefore, there is a need to minimize real-time processing effort yetat the same time providing complete coverage of possible errorconditions in reporting and re-transmitting only those informationframes that are out of sequence. The subject invention herein solvesthis problem in a new and unique manner that has not been part of theart previously.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a methodand system for continuously linking within a telecommunication system orinformation handling system.

It is yet another object of the present invention to provide a methodand system for minimizing real-time processing effort yet at the sametime providing complete coverage of possible error conditions within atelecommunication or information handling system.

It is still yet another object of the present invention to provide amethod and system for reporting and re-transmitting only thoseinformation frames that are out of sequence within a telecommunicationor information handling system.

The foregoing objects are achieved as is now described. A method andsystem for partial reporting of missing sequence numbered informationframes within a telecommunication system using selective reject (SREJ)frames is disclosed. Upon receiving a sequence numbered informationframe from a transmit terminal, a receive terminal determines if it isout of sequence. If the sequence numbered information frame is out ofsequence, the receive terminal further checks the sequence numberedinformation frame to see if a poll bit has been set. If the poll bit isnot set, the receive terminal further checks to see if the sequencenumbered information frame is new or retransmitted. If the sequencenumbered information frame is new, a list of missing sequence numbers isconstructed beginning with the missing sequence number one greater thanthe largest number in the receive queue and ending with N(S)−1. If thesequence numbered information frame is retransmitted, a list of missingsequence numbers is constructed beginning with the next smaller missingsequence number in the receive queue plus one and ending with N(S)−1.Thereafter, a select reject frame (SREJ) is sent to the transmitterminal containing a list of the out-of-sequence numbered informationframe(s) for retransmittal.

The above as well as additional objects, features, and advantages of thepresent invention will become apparent in the following detailed writtendescription.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the invention are setforth in the appended claims. The invention itself however, as well as apreferred mode of use, further objects and advantages thereof, will bestbe understood by reference to the following detailed description of anillustrative embodiment when read in conjunction with the accompanyingdrawings, wherein:

FIG. 1 depicts a block diagram of a Integrated Services Digital Networkin which a preferred embodiment of the present invention may beimplemented;

FIG. 2 is a high level block diagram of an air-interface model in whicha preferred embodiment of the present invention may be implemented;

FIG. 3 depicts a SREJ response frame in accordance with a preferredembodiment of the present invention;

FIG. 4 is a high-level logic flow diagram of a method for partialreporting of missing sequence numbered information frames in accordancewith a preferred embodiment of the present invention;

FIG. 5 is a continuation of the high-level logic flow diagram shown inFIG. 4, and

FIG. 6 is a diagram depicting one scenario in which the preferredembodiment of the present invention may be used.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

With reference now to the figures and in particular with reference toFIG. 1, there is depicted a block diagram of an illustrative embodimentof a telecommunication system with which the present invention mayadvantageously be utilized. The illustrative embodiment depicted in FIG.1 is a computer workstation linked into an Integrated Services DigitalNetwork, however, as will become apparent from the followingdescription, the present invention may also be applied to any type ofdata processing, telephony or information handling system.

As illustrated in FIG. 1, the telecommunication system 10 includes acomputer workstation or data processing system 12 linked to anIntegrated Services Digital Network (ISDN) 18. In the depictedembodiment, the computer 12 is connected or linked to a switch stream 20within the ISDN 18 through a modem 22. To ensure that voice andsignaling or data and signaling information can be transmittedsimultaneously within the ISDN 18, multiple channels are provided asdefined by the International Telecommunication Union (ITU) in a seriesof protocol specifications. These channels are identified as B-channelsand D-channels respectively. The B-channels are used for informationtransfer, such as speech, text, data and images. As shown in FIG. 1, theD-channel is used for call control signaling procedures and may also beused to carry packet-switched data. The call control signalinginformation on the D-channel is used to establish, supervise and releasethe circuit-switched connections 20 being requested for.

Referring once again to FIG. 1, there is shown an Open SystemsInterconnection (OSI) model 16 for depicting a layered signalingprotocol architecture used for link establishment and data communicationflow within the telecommunication system 10. The model 16 provides forseven layers of interactions that occur between terminals and aredefined by the International Telecommunications Union (ITU) in a seriesof protocol specifications. As shown in FIG. 1, the Link Access Protocolfor the D-channel (LAPD) defined by the ITU-T Q.921 protocolspecification is the second layer (Layer-2) 14 with the ITU-T Q.931protocol specification defining the third layer (Layer-3) 24.

Turning now to FIG. 2, a high level block diagram depicting an airinterface model for cellular messaging 30 which also uses the OSI sevenlayered model shown in FIG. 1 in accordance with the present inventionis illustrated. As shown in FIG. 2, the first layer (Layer-1) 26 is aphysical layer that deals with the radio interface, burst, slots,frames, and superframes in telecommunication interactions. The secondlayer 14 (Layer-2) is the data link that handles the data packaging,error correction and is the layer in which the method of the preferredembodiment of the present invention is applied. The third layer 24(Layer-3) is the message layer, which creates, and handles messages sentand received across the air. The remaining four upper application layersrepresent the teleservice 28 currently being used, such as voice andmessaging transactions, or future services like on-air programming.

Referring now to FIG. 3, there is shown a selective reject frame SREJframe 32 that is sent by a transmit terminal along the Layer-2 D-channelfor decoding by a receive terminal when the transmit terminal isreporting missing frame(s) for retransmittal that will be more fullydescribed below. The frame 32 is structured or formatted in accordancewith the ITU-T Q.921 protocol specification and consists of a variable Nbytes each having a length of eight (8) bits 34. As shown in FIG. 3, atthe start 36 and end 44 of frame 32 is a flag sequence consisting of one0 bit followed by six contiguous 1 bits and one zero. The flag precedingthe address field 38 is defined as the opening flag 36 and the flagfollowing the Frame Check Sequence (LSB) 43 is defined as the closingflag 44 so that the receiving terminal knows to decode the informationformatted between the opening and closing flags.

Referring once again to FIG. 3, the frame 32 includes an address fieldformat which contains the address field extension bits, acommand/response bit (C/R), a data link layer Service Access PointIdentifier (SAPI) subfield 37, and a Terminal Endpoint Identifier (TEI)subfield 38. These two bytes define the type of application thattransfers messages on the data link connections carried on theD-channel. The SAPI 37 identifies a point at which data link layerservices are provided by a data link layer entity to a Layer-3 ormanagement entity. The control field 40 is shown as the fourth and fifthbyte and identifies the sequence number of the next expected (oldest andfirst missing) frame referred to as N(R). It is this field that isdecoded by a receive terminal when missing frames are being reported inaccordance with the ITU-T Q.921 specification. The information field 46lists a sequence of missing frames, sequentially, if there is more thanone missing frame, as will be more fully described below. The framecheck sequence bytes MSB 42 and LSB 43 are used for transmission errorchecking. In operation, the transmit terminal sends out the SREJ frame32 with the control field parameters 40 set and a list of missing frameswhich are decoded by a receive terminal. The transmit terminal uponreceiving the SREJ frame retransmits those listed missing frames back tothe receive terminal.

Referring now to FIG. 4, there is shown a high-level logic flow diagramof a method for partial reporting of missing sequence numberedinformation frames in accordance with a preferred embodiment of thepresent invention. As shown in step 100, at the layer 2 or data linklayer 14, a receive terminal receives a sequence numbered informationframe from a transmit terminal wherein the receive terminal determinesif it is out of sequence. The receive terminal does this by checking thesequence numbered information frame to see if N(S) is equal to a statevariable V(R), as shown in step 102. Given the exchange of informationframes between two terminals (a transmit and receive terminal) using theLAPD protocol, N(S) is the sequence number of the received sequencenumbered information frame and V(R) is the sequence number of the nextexpected sequence numbered information frame that the receive terminalis expecting. By way of example but not of limitation, if V(R) issequence numbered information frame “ten”, the expected sequencenumbered information frame, and N(S) is sequence numbered informationframe “ten”, the received sequence numbered information frame, then N(S)equals V(R) and the expected sequence numbered information frame hasbeen received.

Referring once again to FIG. 4, when N(S) equals V(R), the processproceeds to step 104, wherein the receive terminal determines if thesequence numbered information frame has been retransmitted. If theinformation frame has not been retransmitted the process proceeds tostep 106, wherein the sequence numbered information frame is added tothe head of the receive terminal's receive queue. Next, in step 108, thereceive terminal increments V(R) by one, the next in-sequence numberedinformation frame expected to be received. When the receive terminalreceives the first frame and consecutive in-sequence frames thereafterthey are passed up to layer 3 or the message layer 14, as shown in step110. The receive terminal may acknowledge to the transmit terminal, asshown in step 112, that it has received all sequence numberedinformation frames and ends at 128. The process repeats itself when thereceive terminal receives subsequent sequence numbered informationframes from the transmit terminal.

Turning once again to FIG. 4, if in step 104 the sequence numberedinformation frame is a retransmitted frame it is placed as shown in step116 into the receive terminals receive queue. The receive terminal thenincrements V(R) by one, shown in step 118 and passes the sequencenumbered information frame just placed in the receive queue if insequence to layer 3 or the data layer 14, as shown in step 120. Whenreceiving a sequence numbered information frame that has beenretransmitted and placed in the queue, the queue is checked to see ifmore sequence numbered information frames are now in-sequence, as shownin step 122. If there are more in-sequence numbered information framesin the receive queue, the process loops through steps 118 and 120,incrementing the next expected sequence numbered information frame andpassing that information to the message layer 14 until an out ofsequence event occurs. The receive terminal then checks to see if itsreceive queue is empty, step 124, and if it is then it clears a SREJexception since it expects no retransmitted frames. Once again, thereceive terminal may acknowledge to the transmit terminal, as shown instep 112, that it has received all sequence numbered information framesand ends at 128, or the process begins again at step 100 to receive thenext information frame. However, if the receive terminal still hasinformation frames in its receive queue, then one or more in-sequenceinformation frames have still not been received. In this state, thereceive terminal still waits to receive more information frames, sendsout an acknowledgement if necessary and does not send a SREJ responseframe, as shown in steps 126 and 112. The process in which a selectivereject SREJ response frame 32 is now described below with reference toFIG. 5.

With reference now to FIGS. 4 and 5, if N(S) does not equal V(R), thenthe information frame is out-of-sequence and the receive terminal checksto see if the received sequence numbered information frame has beenretransmitted, shown as step 129 in FIG. 5. Continuing to refer to FIG.5, if the sequence numbered information frame was not retransmitted,then as shown in step 134, it is added to the head of the receiveterminal's receive queue. The process then proceeds to step 136 and setsan SREJ response exception state. The SREJ response is used to initiatea more efficient error recovery by selectively requesting theretransmission of one or more information frames following the detectionof sequence errors. The receive terminal then checks the sequencenumbered information frame to see if its poll bit has been set, as shownin step 138.

If the information frame has its poll bit set to or equal to one thenthe transmit terminal indicates that it has retransmitted all requiredor previously requested sequence numbered information frames and thereceive terminal constructs a complete list of missing frames and placesthe list in information field 46 of the SREJ frame 32 and assigns thevalue of the poll bit to an F bit in SREJ frame 32, as shown in steps144 and 146. Setting the F bit indicates to the transmit terminal thatthe receive terminal has acknowledged receipt of a frame with a poll bitset. The receive terminal then sends the SREJ response frame 32 to thetransmit terminal, as shown in step 148, to prompt the transmit terminalto retransmit the missing sequence numbered information frames listed ininformation field 46 and N(R) 41, the second byte of the control field.

If the sequence numbered information frame has its poll bit set to zeroand it is received out-of-sequence and also not a retransmitted frame,then the receive terminal constructs a list of missing sequence numberedinformation frames by starting with the highest sequence numbercurrently in the receive queue plus one and ending with N(S)−1, whereinthe first byte goes into the N(R) 41 field and the remainder of the listis placed in the information field 46 of the SREJ frame 32, as shown instep 142. The receive terminal then assigns the value of the poll bit tothe F bit in SREJ frame 32, as shown in step 150. Once again, settingthe F bit indicates to the transmit terminal that the receive terminalhas a frame with the poll bit set. The receive terminal then sends theSREJ response frame 32 to the transmit terminal, as shown in step 148,to prompt the transmit terminal to retransmit the missing sequencenumbered information frames listed in N(R) field 41 and informationfield 46.

Referring once again to FIG. 5, if in step 129 the sequence numberedinformation frame was retransmitted it is inserted in the propersequence location in the receive terminal's receive queue as shown instep 130. The receive terminal once again checks to see if the poll bitis set to or equal to one as shown in FIG. 131. If the poll bit is equalto one, the receive terminal constructs a complete list of missingframes and places the list in information field 46 and N(R) field 41 ofthe SREJ frame 32 and assigns the value of the poll bit to the F bit inSREJ frame 32, as shown in steps 144 and 146. The receive terminal thensends the SREJ response frame 32 to the transmit terminal, as shown instep 148, to prompt the transmit terminal to retransmit the missinginformation frames and N(R) 41 listed in information field 46.

If the poll bit does not equal one having a value of zero and the framehas been retransmitted, the sequence numbered information frame ischecked to see if the preceding sequence numbered information frame isN(S)−1 in the receive queue, shown in step 132. If the precedingsequence numbered information frame “N(S)−1” is in the receive queue,then no SREJ frame response is required because a SREJ frame has alreadybeen sent, as shown in step 141. However, if in step 132, N(S)−1 is notin the receive queue the receive terminal then constructs a list ofmissing sequence numbered information frames by starting with one plusthe next smaller sequence number currently in the receive queue thanN(S) and ending with N(S)−1 and places this list in information field 46and first byte N(R) 41 of the SREJ frame 32, as shown in step 142. Thereceive terminal then assigns the value of the poll bit to the F bit inSREJ frame 32, as shown in step 146. Once again, setting the F bitindicates to the transmit terminal that the receive terminal has a framewith the poll bit set. The receive terminal then sends the SREJ responseframe 32 to the transmit terminal, as shown in step 148, to prompt thetransmit terminal to retransmit the missing information frames listed ininformation field 46 and N(R) 41.

Referring now to FIG. 6, there is shown a diagram depicting one scenarioin which the preferred embodiment of the present invention may be used.As shown in FIG. 6, the point-to-point data link between terminal A 160and terminal B 162 is initially subjected to a severe error condition(possibly a microwave fade on a microwave link), causing frames 0through 6 172 to be lost in transmit. Frame 7 174 gets through toterminal B 162 which prompts a SREJ response 164 to be sent requestingretransmission of frames 0-6 172 (so far the actions are dictated by theexisting Q.921 standard). Meanwhile, terminal A 160 continues to sendInformation “I” frames to terminal B 162. It has already sent frames 8through 12 before it receives the SREJ response 164 from terminal B 162.Upon receiving the SREJ, it immediately goes into the Timer RecoveryMode 176 (restarting timer T200) and commences retransmission beginningat frame 0. Note that frames 8 through 10 have been lost in transmit. Soupon receiving frame 11 out of sequence, terminal B 162 constructs alist missing frames starting at one greater than the largest sequencenumber currently in the receive queue (7+1=8) and ending atN(S)−1=11−1=10 (so the SREJ frame contains sequence numbers 8 through10). This is described above in detail with reference to FIGS. 4 and 5.In the middle of retransmitting (right after frame 3) due to the firstSREJ 164, terminal A 160 receives the second SREJ 166, and the listedframes are marked for retransmission.

As shown in FIG. 6, the retransmitted frames 1 and 2 178 have been lostin transmission. Upon receiving frame 3, terminal B 162 constructs alist of missing frames starting at one greater than the next smallersequence number in the receive queue (0+1=1) and ending at N(S)−1=3−1=2(so the SREJ frame contains sequence numbers 1 and 2) and sends anotherSREJ response 168. Once again, this is described above in detail withreference to FIGS. 4 and 5. Meanwhile, terminal A 160 continuesre-transmitting due to the two earlier SREJ frames 164 and 166,respectively. It should be noted that terminal B does not send a SREJframe after step 168 because the N(S)−1 check fails, indicating that aSREJ frame has already been sent. After transmitting frame 9, itreceives the SREJ and retransmits the requested frames (1 and 2). Itthen retransmits the last outstanding frame (10), sets the Poll bit,clears the SREJ exception, and restarts timer T200 178.

The present invention provides for a telecommunication system thatmaintains communication between terminals in the presence of real timeerrors. The method and system of the present invention is unique in thatthe ITU-T protocol specification provides no procedure for certainsequence error conditions which may arise on links using the LAPDprotocol for which the standard provides no method of handling.

It is also important to note that although the present invention hasbeen described in the context of a fully functional telecommunicationsystem, those skilled in the art will appreciate that the mechanisms ofthe present invention are capable of being distributed as a programproduct in a variety of forms to any type of information handlingsystem, and that the present invention applies equally regardless of theparticular type of protocol utilized to actually establish a linkconnection. Examples of signal bearing media include, withoutlimitation, recordable type media such as floppy disk or CD ROMs andtransmission type media such as analog or digital communications links.

While the invention has been particularly shown and described withreference to a preferred embodiment, it will be understood by thoseskilled in the art that various changes in form and detail may be madetherein without departing from the spirit and scope of the invention.

What is claimed is:
 1. A method for partial reporting of missinginformation frames within a telecommunication system, comprising thesteps of: receiving a sequence numbered information frame from atransmit terminal at a receive terminal; determining if said sequencenumbered information frame is out of sequence; responsive to determiningsaid sequence numbered information frame is out of sequence, determiningif a poll bit is set; responsive to determining that said poll bit isnot set, determining if said sequence numbered information frame is new;responsive to determining said sequence numbered information frame isnew, constructing a list of missing sequence numbered information framesbeginning with a missing sequence number one greater than the largestsequence number in said receive terminal's receive queue and ending withsaid sequence numbered information frame minus one; and sending aselective reject SREJ frame response to said transmit terminalcontaining said list of missing sequence numbered information frames forre-transmittal.
 2. The method for partial reporting of missinginformation frames within a telecommunication system according to claim1, wherein the step of determining if said sequence numbered informationframe is new; further comprises: determining said sequence numberedinformation frame is retransmitted and said poll bit is set to zerothereby constructing a list of missing sequence numbered informationframes beginning with a smallest missing sequence number plus one andending with said sequence numbered information frame minus one; andsending a selective reject SREJ frame response to said transmit terminalcontaining said list of missing numbered information frames forre-transmittal.
 3. The method for partial reporting of missinginformation frames within a telecommunication system according to claim1, wherein the step of sending a selective reject frame furthercomprises: assigning an F bit in said SREJ frame to the value of saidpoll bit.
 4. The method for partial reporting of missing informationframes within a telecommunication system according to claim 2, whereinthe step of sending a selective reject frame further comprises:assigning an F bit in said SREJ frame to the value of said poll bit. 5.The method for partial reporting of missing information frames within atelecommunication system according to claim 1, wherein the step ofsending a selective reject frame further comprises: setting apredetermined T200 time interval.
 6. The method for partial reporting ofmissing information frames within a telecommunication system accordingto claim 1, wherein the step of receiving a sequence numberedinformation frame further comprises: passing said sequence numberedinformation frame to an upper layer when said sequence numberedinformation frame is in-sequence.
 7. The method for partial reporting ofmissing information frames within a telecommunication system accordingto claim 1, wherein the step of determining if said sequence numberedinformation frame is out of sequence further comprises: Comparing saidsequence numbered information frame's sequence number N(S) to a statevariable V(R) wherein V(R) is a sequence number of a next expectedsequence numbered information frame.
 8. The method for partial reportingof missing information frames within a telecommunication systemaccording to claim 1, wherein the step of determining if said sequencenumbered information frame is out of sequence further comprises:inserting said sequence numbered information frame into a properlocation of said receive terminal's receive queue.
 9. The method forpartial reporting of missing information frames within atelecommunication system according to claim 1, wherein the step ofdetermining if said sequence numbered information frame is new; furthercomprises: determining said sequence information frame is retransmittedand said poll bit is set to one thereby constructing a complete list ofmissing sequence numbered information frames and sending a selectivereject SREJ frame response to said transmit terminal containing saidlist of missing sequence numbered information frames for re-transmittaland assigning an F bit to the value of said poll bit.
 10. The method forpartial reporting of missing information frames within atelecommunication system according to claim 6, wherein the step ofpassing said sequence numbered information frame to a data layer whensaid sequence numbered information frame is in-sequence furthercomprises: clearing a SREJ exception when said receive queue of saidreceive terminal is clear.
 11. An information handling system,comprising: means for receiving a sequence numbered information framefrom a transmit terminal at a receive terminal; means for determining ifsaid sequence numbered information frame is out of sequence; means fordetermining if a poll bit is set when said sequence numbered informationframe is out of sequence; means for determining if said sequencenumbered information frame is new when said poll bit is not set; meansfor constructing a list of missing sequence numbered information framesbeginning with a missing sequence number one greater than the largestsequence number in said receive terminal's receive queue and ending withsaid sequence numbered information frame minus one when said sequencenumbered information frame is new; and means for sending a selectivereject SREJ frame response to said transmit terminal containing saidlist of missing sequence numbered information frames for re-transmittal.12. An information handling system according to claim 11, furthercomprising: means for constructing a list of missing sequence numberedinformation frames beginning with a smallest missing sequence numberplus one and ending with said sequence numbered information frame minusone when said sequence numbered information frame is re-transmitted andsaid poll bit is set to zero; and means for sending a selective rejectSREJ frame response to said transmit terminal containing said list ofmissing sequence numbered information frames for re-transmittal.
 13. Aninformation handling system according to claim 11, further comprising:means for assigning an F bit in said SREJ frame to the value of saidpoll bit.
 14. An information handling system according to claim 12,further comprising: means for assigning an F bit in said SREJ frame tothe value of said poll bit.
 15. An information handling system accordingto claim 11, further comprising: means for setting a predetermined T200time interval.
 16. An information handling system according to claim 11,further comprising: means for passing said sequence numbered informationframe to a data layer when said sequence numbered information frame isin-sequence.
 17. An information handling system according to claim 11,further comprising: means for comparing said sequence numberedinformation frame's sequence number N(S) to a state variable V(R)wherein V(R) is a sequence number of a next information frame.
 18. Aninformation handling system according to claim 11, further comprising:means for determining said sequence numbered information frame isretransmitted and said poll bit is set to one thereby constructing acomplete list of missing sequence numbered information frames andsending a selective reject SREJ frame response to said transmit terminalcontaining said list of missing sequence numbered information frames forre-transmittal and assigning an F bit to the value of said poll bit. 19.An information handling system according to claim 16, furthercomprising: means for clearing a SREJ exception when said receive queueof said receive terminal is clear.
 20. A computer program productresiding on a computer usable medium for upgrading a terminal toterminal link within an information handling system, comprising:instruction means for receiving a sequence numbered information framefrom a transmit terminal at a receive terminal; instruction means fordetermining if said sequence numbered information frame is out ofsequence; instruction means for determining if a poll bit is set whensaid sequence numbered information frame is out of sequence; instructionmeans for determining if said sequence numbered information frame is newwhen said poll bit is not set; instruction means for constructing a listof missing sequence numbered information frames beginning with a missingsequence number one greater than the largest sequence number in saidreceive terminal's receive queue and ending with said sequence numberedinformation frame minus one when said sequence numbered informationframe is new; and instruction means for sending a selective reject SREJframe response to said transmit terminal containing said list of missingsequence numbered information frames for re-transmittal.